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The automotive area has improved its technology in order to make combustion engines achieve higher rates of delivered power, fuel economy and lower pollution emissions. Such factors are directly influenced by the detonation phenomenon or knock, that happens under high temperature and torque requests and it may be detected by a knock sensor and proper signal processing techniques. The accurate identification of detonation, such as its intensity and time length, allows a better identification of threshold conditions that cause this phenomenon. Moreover, a special case is the flex fuel engines (work with ethanol and/or gasoline), in which the detonation identification may show which kind of fuel is being used, allowing an optimized engine management. This work focus on the identification and characterization of the knock phenomenon signal utilizing power estimators and adaptive filters. First, a simple signal model is considered.

Vehicles equipped with original tri-fuel engines are restricted to a few models. They can operate on blends of liquid fuels, but the use of CNG does not occur simultaneously. CNG is often used by converted vehicles and can be used with ethanol, gasoline or a mixture of both. The main disadvantages in the use of CNG are low volumetric efficiency, low autonomy, loss of power and the need for internal space to store the cylinder. However, they have great economic advantages. The main goal of this project is to build an electronic circuit able to efficiently manage the injection of CNG, increasing its volumetric efficiency and minimizing the loss of power through an automatic management of the power and economy ratio. When the power demand is low, the system operates only on CNG. When intermediate power is required, the system operates with different proportions of ethanol and CNG. For maximum power, only ethanol is used.